Title

Densities And Terminal Velocities

Problem Scenario

Broad Question

Does the density of an object change the terminal velocity?

Specific Question

If I modify the density of a tennis ball, will its terminal velocity change?

Hypothesis

If the density of an the tennis ball is higher, the higher the terminal velocity of the object.

Graph of Hypothesis

Variables

Independent Variable: Density of ball

Dependent Variable: Terminal velocity

Variables That Need To Be Controlled:

Distance and angle ball flies.

Vocabulary List That Needs Explanation

Terminal Velocity: the max speed something will go before it drops.

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General Plan

I will change the density of a tennis ball by adding some type of liquid or gas to change the density. Then, I will use a tennis ball launcher to shoot a tennis ball and find its speed. Then, i will turn speed into terminal velocity. I will record the data in a data table, average the numbers, and use the average to see which density of ball has a higher or lower terminal velocity.

Potential Problems And Solutions

I can't measure the speed of the tennis ball.
A modified tennis ball won't shoot.

Safety Or Environmental Concerns

Someone getting hit with a ball.

Experimental Design

Controlled, manipulated experiment

What is your experimental unit?

Terminal Velocity.

Number Of Trials:

5

Number Of Subjects In Each trial:

2

Number of Observations:

5

When data will be collected

My data will be collected the 16th-24th of February.

Where will data be collected?:

Cranmore and my house

Resources and Budget Table

Item	Number needed	Where I will get this	Cost
Tennis ball shooter	1	Cranmore	not sure
Tennis balls	10	Walmart	not sure
Radar gun app	1	App store	1.99

Detailed Procedure

1. Test the shooting speed and angle
2. Take speed of tennis ball
3. Record in table
4. Change the speed to the terminal velocity
5. Repeat steps 2-4 four more times
6. Average the terminal velocities
7. Repeat with a modified ball
8. Compare

Diagram

Photo List

Time Line

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Data Table

	0 BB's	50 BB's	100 BB's	150 BB's
#1	153	203	227	271
#2	171	221	231	263
#3	155	196	251	250
#4	139	221	237	249
#5	187	189	243	269
Averages	161	206	237.8	260.4

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Data Analysis

All Raw Data

Graphs

Photos

Results

The higher the density, the higher the the terminal velocity.

Conclusion

My conclusion is that if two objects have the same shape but different densities, the one with a higher density would have a higher terminal velocity. This is true with most objects. The gravitational pull will pull harder on things with a higher mass.

Discussion

Benefit to Community and/or Science

This will further the understanding of speed and mass for younger people who don't quite grasp physics.

Background Research

The mass of a standard BB pellet is roughly five grams depending on factors like a difference in the making or rust that has developed on the BB. Terminal velocity is measured in.
Mathematically, terminal velocity—without considering buoyancy effects—is given by

V_t= sqrt{frac{2mg}{rho A C_d }}

where
= terminal velocity,

m

= mass of the falling object,

g

= acceleration due to gravity,

C_d

= Drag coefficient,

rho

= Density of the fluid through which the object is falling, and

A

= projected area of the object.The weight of a standard Tennis ball is roughly 56 to 59.4 grams.

References

Abstract